Renal and hypertensive complications of extracorporeal shock wave lithotripsy (ESWL): which patients are at risk?

Histological and functional consequences of ESWL: Extracorporeal shock wave litotripsy is now used for the treatment of about 90% of stones. Because o f the non-punctual delivery of energy into the stone, a small volume of ren al parenchyma is injured, giving rise to a fibrous scar which can be visual ized by morphological techniques such as magnetic nuclear resonance. Isotop ic techniques point out a 15% reduction of renal plasma flow on the side of the litotripsy. For a majority of patients, this alteration is transient. Hypertension: In a few cases, abrupt onset of transient hypertension has be en reported in clear relation with a compressive perirenal hematoma. The ca usal effect of ESWL on late occurrence of permanent hypertension is however still uncertain, probably because of the difficulty to show that this occu rrence is not related to the older age of the patient alone. The FDA sponso red multicentric study begun in 1993 should solve this issue in the future. Patients at risk: Recent articles suggest that altered renal function prior to ESWL would predict late occurrence of hypertension and worsening of ren al failure. Furthermore, age and the resistance index of arcuate or interlo bular renal arteries (measured by Doppler) could help to screen the patient s at risk of developing hypertension. Practical attitude: in practice, rena l function and blood pressure should be carefully monitored in patients age d over 60 and/or who have a serum creatinine > 300 mu mol/l.